Status Update Performance in Uplink Massive MU-MIMO Short-packet Communication Systems

Timely status updates are becoming more and more important in some future Internet of Things (IoT) applications, such as unmanned driving and intelligent home. In this paper, we investigate a multiuser multiple-input-multiple-output (MU- MIMO) short-packet communication system under perfect channel state information consisting of the next generation Node B (gNB) with multiple antennas and several users with a single antenna. We use the average age of information (AoI) as the performance parameter and the zero-forcing (ZF) detection to minimize the mutual interference. We analyze the status update process in the finite blocklength system and derive an approximated closed-expression of the average AoI. Monte Carlo simulation and numerical results verify that in the MU-MIMO system status update performance can be improved by increasing the transmit power and arranging multiple antennas, and show that there is an optimal packet blocklength which can lead to the best status update performance.